Abnormal heart rhythms, or arrhythmias, may cause various types of symptoms, such as loss of-consciousness, palpitations, dizziness, or even death. An arrhythmia that causes symptoms such as these is usually a marker of significant underlying heart disease in the conduction system. It is important to make the diagnosis that these symptoms are due to an abnormal heart rhythm since treatment with various procedures, such as pacemaker implantation or percutaneous catheter ablation, can successfully ameliorate these problems and prevent significant morbidity and mortality.
Since these symptoms can often be due to other, less serious causes, a key challenge is to determine when any of these symptoms are due to an arrhythmia. Oftentimes, arrhythmias occur infrequently and/or episodically making rapid and reliable diagnosis difficult. Currently, cardiac rhythm monitoring is primarily accomplished through the use of devices utilizing short-duration (<1 day) electrodes affixed to the chest. Wires connect the electrodes to a recording device, usually worn on a belt or at the waist. The electrodes need daily changing and the wires are cumbersome. The devices also have limited memory and recording time. Wearing the device interferes with patient movement and often precludes performing certain activities while being monitored, such as bathing. All of these limitations severely hinder the diagnostic usefulness of the device, the compliance of patients using the device and the likelihood of capturing all important information. Lack of compliance and the shortcomings of the devices often lead to the need for additional devices, follow-on monitoring or other tests to make a correct diagnosis.
Current methods to correlate symptoms with the occurrence of arrhythmias, including the use of cardiac rhythm monitoring devices such as Holter monitors and cardiac event recorders, are often not sufficient to allow an accurate diagnosis to be made. In fact, Holter monitors have been shown to not lead to a diagnosis up to 90% of the time (“Assessment of the Diagnostic Value of 24-Hour Ambulatory Electrocariographic Monitoring”, by DE Ward et al. Biotelemetry Patient Monitoring, vol. 7, published in 1980).
Additionally, the medical treatment process to actually obtain a cardiac rhythm monitoring device and initiate monitoring is very complicated as illustrated in FIGS. 1 and 2. As is made clear by reviewing FIGS. 1 and 2, there are numerous steps involved in ordering, tracking, monitoring, retrieving, and analyzing the data from the device. In most cases, the patient must go to a separate office or facility to obtain the cardiac rhythm monitoring device. The difficulty posed by these factors leads to fewer patients receiving cardiac rhythm monitoring since physicians may be reluctant to go through the paperwork and burden required to initiate monitoring for a potentially lower-risk patient who presents with mild symptoms.
Once monitoring has been initiated, a large component of the process today involves a 3rd party cardiac rhythm monitoring company which is contacted, either by the patient or directly by the device, when symptoms or certain parameters set in the device are met. The screening algorithms used by devices to automatically determine if certain parameters have been met are usually simple and not very specific since the ability to process complex electrocardiogram (ECG) data is not possible in these devices due to size, cost, and a limited ability and understanding of how to process ECG signals accurately. The 3rd party monitoring company will then retrieve the data from the device over the telephone or wirelessly from the device, and will contact the patient's physician if particular parameters are met. Though this step can be useful in some instances, for the vast majority of patients it is unnecessary and only results in a physician being needlessly contacted, often in the late hours of the night. It is extremely rare for the physician to recommend that the patient go to the hospital or emergency room to be treated at the time the physician was notified.
Further, the majority of devices used today are ordered by a cardiologist or a cardiac electrophysiologist (EP), rather than the patient's primary care physician (PCP). This is of significance since the PCP is often the first physician to see the patient and make the connection that the patient's symptoms could be due to an arrhythmia. After the patient sees the PCP, the PCP will make an appointment for the patient to see a cardiologist or an EP. This appointment is usually several weeks from the initial visit with the PCP, which in itself leads to a delay in making a potential diagnosis as well as increases the likelihood that an arrhythmia episode will occur and go undiagnosed. When the patient finally sees the cardiologist or EP, a cardiac rhythm monitoring device will usually be ordered. The monitoring period can last 24-48 hours (Holter monitor) or up to a month (cardiac event monitor). Once the monitoring has been completed, the patient must return the device, which itself can be a hassle for the patient. After the data has been processed by the monitoring company or by a technician on-site at a hospital or office, a report will finally be sent to the cardiologist or EP for analysis.
In view of the shortcomings in cardiac rhythm monitoring and the processes to utilize data collected by cardiac rhythm monitoring systems, there is a need for improved non-invasive cardiac monitoring devices and methods.